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                <p><strong>创建数据库</strong> create database 数据库名;</p>
<p><strong>查看数据库</strong> show databases;</p>
<p><strong>选择数据库</strong> use 数据库名;</p>
<p><strong>删除数据库</strong> drop database 数据库名;</p>
<p><strong>清空数据库</strong> truncate 数据库名;</p>
<p><strong>创建表</strong> create table 表名(属性名1 数据类型 ，属性名2 数据类型 . . . . . .  );</p>
<p><strong>查看表结构</strong> desc 表名;</p>
<p><strong>查看建表语言</strong> show create table 表名;</p>
<p><strong>表中新增字段</strong> alter table 表名 add( 属性名1 数据类型，属性名2 数据类型…..);</p>
<p><strong>在表的第一个位置增加字段</strong> alter table 表名 add 属性名 数据类型 first;</p>
<p><strong>在指定字段后面增加字段</strong> alter table 表名 add 新增属性名 数据类型 after 属性名;</p>
<p><strong>删除表中字段</strong> alter table 表名 drop 属性名;</p>
<p><strong>删除表</strong> drop table (if exists 有无都可) 表名;</p>
<p><strong>修改表名</strong>alter table 旧表名 rename 新表名; 或alter table 旧表名 rename to 新表名;</p>
<p><strong>修改表中字段的数据类型</strong> alter table 表名 modify 需要修改的属性名 想要修改成的数据类型;</p>
<p><strong>修改表中字段的默认大小</strong> alter table 表明 modify 需要修改的属性名 属性的原数据类型 default 默认大小</p>
<p><strong>修改表中字段名称</strong> alter table 表名 change 旧属性名 新属性名 旧数据类型;</p>
<p><strong>修改表中字段名称和数据类型</strong> alter table 表名 change 旧属性名 新属性名 新数据类型;</p>
<p><strong>修改表中字段为头字段</strong> alter table 表名 modify 属性名 数据类型 first;</p>
<p><strong>修改字段1为顺序，在字段2后面</strong> alter table 表名 modify 属性名1 数据类型 after 属性名2;</p>
<p><strong>插入数据记录</strong> insert into 表名(字段1,字段2,…..或不写) values(一条数据),(一条数据);</p>
<p><strong>插入查询结果</strong>insert into 要插入表表名 (插入表中字段1，插入表中字段2,…..) select (查询表中字段1,查询表中字段2……) from 要查询表表名 查询语句;</p>
<p><strong>强制插入数据</strong> replace into 表名(字段1,字段2,…..或不写) values (一条数据);</p>
<p><strong>更新数据记录</strong> update 表名 set 字段1=新值， 字段2=新值………where 查询语句；</p>
<p><strong>删除数据记录</strong> delete from表名 where 查询语句；</p>
<p><strong>查询部分数据记录</strong> select 字段1，字段2 …… from 要查询的表；</p>
<p><strong>避免重复查询</strong> select distinct 字段1，字段2 …… from 要查询的表；</p>
<p>**为查询结果起别名 **select 字段1 as或不写 别名1，字段2 as或不写 别名2 …… from 要查询的表；</p>
<p><strong>设置显示格式数据查询</strong> select concat（字段1，‘提示语句’，字段2 …… ） from 要查询的表；</p>
<p><strong>where条件查询</strong> select * from 表名 where 字段=值；</p>
<p><strong>between and 关键字范围查询</strong> select * from 表名 where 字段 between 值1 and 值2；</p>
<p><strong>between and 关键字不再范围内查询</strong> select * from 表名 where 字段 not between 值1 and 值2 ；</p>
<p><strong>带null关键字空查询</strong> select <em>from 表名 where 字段 is not null； 或 select</em> from 表名 where 字段 is not null；</p>
<p><strong>带in关键字的集合查询</strong> select 字段1 ，字段2 …… from 表名 where 字段n in（值1，指2 …… ）；</p>
<p><strong>带like关键字的模糊查询</strong> select <em>from 表名 where 字段 like ‘字段串%’ ； 或select</em> from 表名 where 字段 like ‘字段串_’ ； 或 select * from 表名 where not 字段 like ‘字段串_’ ；</p>
<p><strong>排序数据查询</strong> select * from 表名 order by 依照排序的字段名 asc（升序） 或 desc （降序）；</p>
<p><strong>多字段排序</strong> select * from 表名 order by 字段1 asc ，字段2 desc  …… ；</p>
<p><strong>带limit关键字的限制查询数量</strong> select * from 表名 where limit 开始条数位置 ，显示条数；</p>
<p><strong>分组数据查询</strong> select * from 表名 group by 字段； <strong>随机显示出每个分组的一条数据，一般讲分组与统计合起来使用才有意义</strong></p>
<p><strong>带having的分组限定查询</strong> select * from 表名 group by 字段 having 条件；</p>
<p><strong>inner join on内连接</strong> select * from 表1 inner join 表2 on 条件；</p>
<p><strong>自连接</strong>select e.字段 as 别名1，f.字段 as 别名2…..from 表名 as e inner join 表 as f on 条件；</p>
<p><strong>from多表连接</strong> select * from 表1 ， 表 2 … where 条件；</p>
<p><strong>左外连接</strong>select * from 表1 left join 表2 on 条件；</p>
<p><strong>右外连接</strong> select * from 表1 right join 表2 on 条件；</p>
<p><strong>允许重复值的合并查询</strong> select * from 表1 union all 表2 on 条件；</p>
<p><strong>不含重复值的合并查询</strong> select * from 表1 union 表2 on 条件；</p>
<p><strong>where型子查询</strong> select * from 表名 where （字段1，字段2）=（select 字段1， 字段2 from 表名 where ….）；</p>
<p><strong>in关键字的子查询</strong> select * from 表名 where 字段 in （select ….查询语句）；</p>
<p><strong>any关键字的子查询</strong> select * from 表名 where 字段 &gt;=any （select ….查询语句）；</p>
<p><strong>all关键字的子查询</strong> select * from 表名 where 字段 &lt;= all（select ….查询语句）；</p>
<p><strong>exists关键字的子查询</strong> select * from 表名 where not exists （select ….查询语句）；</p>
<p><strong>regexp正则表达式运算符</strong> select ‘chshs’ rehexp ‘c.’ ；</p>
<h2 id="聚合函数"><a href="#聚合函数" class="headerlink" title="聚合函数"></a>聚合函数</h2><p><strong>计数函数</strong> count（）；</p>
<p><strong>求平均函数</strong> avg（）；</p>
<p><strong>求和函数</strong> sum（）；</p>
<p><strong>取最大函数</strong> max（）；</p>
<p><strong>取最小函数</strong>min（）；</p>
<p><strong>取绝对值</strong>abs（）；</p>
<p><strong>取大于x的最大整数</strong>cell（x）；</p>
<p><strong>取小于x的最大整数</strong>floor（x）；</p>
<p><strong>取数值x的四舍五入后有y位小数</strong>round（x，y）；</p>
<p><strong>直接截取x为有y位的小数</strong>truncate（x，y）；</p>
<p><strong>返回0~1之间的一个随机数</strong> rand（）；</p>
<p><strong>获取第n组返回相同值得随机数</strong> rand（n）；</p>
<p><strong>对字符串进行加密</strong> password（）；</p>
<p><strong>字符串连接函数</strong> concat（字符串1，字符串2…）；</p>
<p><strong>带分隔符字符串合并</strong> concat（分隔符，字符串1，字符串2….）；</p>
<p><strong>返回在字符串str2…中与str1相匹配的字符串位置</strong> find_in_set（‘str1’，‘str2，str3…..’）；</p>
<p><strong>返回字符串str1第一次出现位置</strong> field（‘str1’，‘str2’，‘str3’….）；</p>
<p><strong>返回子字符串str在字符串str1中匹配开始的位置</strong> locate（str，str1）；或 position（str in str1）； 或 instr（str1 ，str）；</p>
<p><strong>返回第n’个字符串</strong> elt（n，str1，str2…strn）；</p>
<p><strong>截取指定位置和长度的字符串</strong> substring（str，num，length）； 或 mid（str，num，length）；</p>
<p><strong>将字符串str从第x位置开始，y个字符长的字串替换为字符串str2</strong> insert（str ， x ，y，str2）；</p>
<p><strong>将字符变为小写</strong> lower（str）；或 lcase（str）</p>
<p><strong>将字符变为大写</strong> upper（str）；或 ucase（str）</p>
<p><strong>获取字符串长度</strong>length（str）；</p>
<p><strong>获取字符数函数</strong>char_length（str）；</p>
<p><strong>返回字符串str中最左边的x个字符</strong> left（str，x）；</p>
<p><strong>返回字符串str中最右边的x个字符</strong> right（str，x）；</p>
<p><strong>使用字符串pad对字符串str最左边进行填充，知道长度为n个字符长度</strong> lpad（str，n，pad）；</p>
<p><strong>使用字符串pad对字符串str最右边进行填充，知道长度为n个字符长度</strong> rpad（str，n，pad）；</p>
<p><strong>去掉字符串str左边的空格</strong> ltrim（str）；</p>
<p><strong>去掉字符串str右边的空格</strong> rtrim（str）；</p>
<p><strong>返回字符串str重复x次的结果</strong> repeat（str，x）；</p>
<p><strong>使用字符串b代替字符串str中的所有字符串a</strong> replace（str，a，b）；</p>
<p><strong>比较字符串str1和str2</strong> strcmp（str1，str2）；</p>
<p><strong>去掉字符串str行头和行尾的空格</strong> trim（str）；</p>
<p><strong>返回字符串str中从x位置起y个长度的字符串</strong> substring（str，x，y）；</p>
<p><strong>获取当前日期</strong>curdate（）； 或 current_date（）；</p>
<p><strong>获取当前时间</strong>curtime（）； 或 current_time（）；</p>
<p><strong>获取当前日期和时间</strong>now（）；或 current_timestamp（） 或 localtime（） 或 systemdate（）；</p>
<p><strong>获取日期date的UNIX时间戳</strong> unix_timestamp（date）；</p>
<p><strong>获取unix时间戳的日期值</strong> from_unixtime（）；</p>
<p><strong>返回日期date为一年中的第几周</strong> week（date）； 或 weekofyear（time）；</p>
<p><strong>返回日期的英文周几</strong> dayname（time）；</p>
<p><strong>返回日期和时间中周几（1：周日，2：周一）</strong> dayofweek（）；</p>
<p><strong>返回日期和时间中周几（0：周一，1：周二）</strong> weekday（）；</p>
<p><strong>返回年中第几天</strong>dayofyear（time）；</p>
<p><strong>返回月中第几天</strong>dayofmonth（time）；</p>
<p><strong>返回日期date的年份</strong> year（date）；</p>
<p><strong>返回时间time的小时值</strong> hour（time）；</p>
<p><strong>返回时间time的分钟值</strong> minute（time）；</p>
<p><strong>返回时间time的月份值</strong> monthname（date）； 或 month（time）</p>
<p><strong>截取日期中的各部分值</strong>extrcat（年或月或日或时或分或秒 from time）；</p>
<p><strong>计算date1与date2之间相隔天数</strong> datediff（date1，date2）；</p>
<p><strong>计算date加上n天后的日期</strong> adddate（date，n）；</p>
<p><strong>计算date减去n天后的日期</strong> subdate（date，n）；</p>
<p><strong>计算time加上n秒后的时间</strong> adddate（time，n）；</p>
<p><strong>计算time减去n秒后的时间</strong> subdate（time，n）；</p>
<p><strong>返回数据库版本号</strong> version（）；</p>
<p><strong>返回当前数据库名</strong> database（）；</p>
<p><strong>返回当前用户</strong> user（）；</p>
<p><strong>将IP地址转化为数字</strong> inet_aton（ip）；</p>
<p><strong>将数字转化为IP地址</strong> inet_ntoa（x）；</p>
<p><strong>创建一个持续时间为time的名为name的锁</strong> cet_loct（name，time）；</p>
<p><strong>为名为name的锁解锁</strong>release_loct（name）；</p>
<p><strong>将表达式重复执行count次</strong> benchmark（count，表达式）；</p>
<p><strong>将x变为type形式</strong> convert（x，type）；</p>
<p><strong>设置字段的非空约束</strong>create table 表名 (属性名 数据类型 not null);</p>
<p><strong>设置字段的默认值</strong> create table 表名 (属性名 数据类型 default 默认值);</p>
<p><strong>设置字段的唯一约束</strong>create table 表名(属性名 数据类型 unique );</p>
<p><strong>设置字段的唯一约束并未约束命名</strong> create table 表名(属性名1 数据类型 ， 属性名2 数据类型 ………. constraint 约束名 unique (属性名1，属性名2……));</p>
<p><strong>设置单字段为主键约束</strong> create table 表名(属性名1 数据类型 primary key….);</p>
<p><strong>设置多字段为主键约束</strong> create table 表名(属性名1 数据类型 , 属性名2 数据类型……..constraint 约束名 primary key (属性名1，属性名2……));</p>
<p><strong>设置字段自动增加值</strong> create table 表名 (属性名 数据类型 auto_increment………);</p>
<p><strong>设置外键约束</strong> create table 表名 (属性名1 数据类型 ， 属性名2 数据类型…….. constraint 外键约束名 foreing key (外键属性名1) references 表名 (主键属性名2));</p>
<p><strong>创建普通索引</strong> create table 表名(属性名 数据类型 ，属性名 数据类型….. index或 key 索引名（可省略）(属性名 (长度（可省略）) asc或desc);</p>
<p><strong>在已存在表创建普通索引</strong>create index 索引名 on 表名 ( 属性名 (长度或不写) asc或desc或不写); 或 alter table 表名 add index或key 索引名(属性名 (长度或不写) asc或desc或不写);</p>
<p><strong>创建唯一索引</strong> create table 表名(属性名 数据类型 ，属性名 数据类型….. unique index或 key 索引名（可省略）(属性名 (长度（可省略）) asc或desc);</p>
<p><strong>创建普通索引</strong> create index 索引名 on 表名（字段名）</p>
<p><strong>创建唯一索引</strong> create unique index 索引名 on 表名（字段名）</p>
<p><strong>创建全文索引</strong> create fulltext index 索引名 on 表名（字段名）</p>
<p><strong>在已存在表创建唯一索引</strong>create unique index 索引名 on 表名 ( 属性名 (长度或不写) asc或desc或不写); 或 alter table 表名 add unique index或key 索引名(属性名 (长度或不写) asc或desc或不写);</p>
<p><strong>创建全文索引</strong> create table 表名(属性名 数据类型 ，属性名 数据类型….. fulltext index或 key 索引名（可省略）(属性名 (长度（可省略）) asc或desc);</p>
<p><strong>在已存在表创建全文索引</strong>create fulltext index 索引名 on 表名 ( 属性名 (长度或不写) asc或desc或不写); 或 alter table 表名 add fulltext index或key 索引名(属性名 (长度或不写) asc或desc或不写);</p>
<p><strong>创建多列索引</strong> create table 表名(属性名 数据类型 ，属性名 数据类型….. index或 key 索引名（可省略）(属性名1 (长度（可省略）) asc或desc ,属性名2 (长度（可省略）) asc或desc………);</p>
<p><strong>在已存在表创建多列索引</strong>create index 索引名 on 表名 (属性名1 (长度（可省略）) asc或desc ,属性名2 (长度（可省略）) asc或desc………); 或 alter table 表名 add index或key 索引名(属性名1 (长度（可省略）) asc或desc ,属性名2 (长度（可省略）) asc或desc………);;</p>
<p><strong>查看索引是否用到</strong> explain select * from 表名 where …….;</p>
<p><strong>删除索引</strong> drop index 索引名 on 表名;</p>
<p><strong>删除索引</strong> alter table 表名 drop index 索引名；</p>
<p><strong>创建视图</strong> create view 视图名 as 查询语句;</p>
<p><strong>查看视图详细信息</strong> show table status from 数据库名 like ‘视图名’; 或 show table status</p>
<p><strong>查看视图定义信息</strong> show create view 视图名;</p>
<p><strong>查看视图设计信息</strong> desc 视图名;</p>
<p><strong>通过系统表查看视图信息</strong> use information_schema ; select * from views where table_name=’视图名’G;</p>
<p><strong>删除视图</strong> drop view 视图名;</p>
<p><strong>修改视图</strong> create or replace view 视图名 as 查询语句; 或 alter view 视图名 as 查询语句 ;</p>
<p><strong>创建触发器</strong>create trigger 触发器名 before或after 触发条件(delete、insert、update) on 触发条件的操作表表名 for each row 触发语句;</p>
<p><strong>创建含多条语句的触发器</strong>delimitercreate trigger 触发器名 before或after 触发条件(delete、insert、update) on 触发条件的操作表表名 for each row begin 触发语句1; 触发语句2；……；end<em>cre<strong>a</strong>t<strong>e</strong>t<strong>r</strong>i<strong>gg</strong>er</em>触发器名<em>b<strong>e</strong>f**ore</em>或<em>a<strong>f</strong>t**er</em>触发条件(<em>d<strong>e</strong>l<strong>e</strong>t**e</em>、<em>in<strong>ser</strong>t</em>、<em>u<strong>p</strong>d<strong>a</strong>t**e</em>)<em>o**n</em>触发条件的操作表表名<em>f<strong>ore</strong>a<strong>c</strong>h<strong>ro</strong>w<strong>b</strong>e<strong>g</strong>in</em>触发语句1;触发语句2；……；<em>e<strong>n</strong>d</em>delimiter;</p>
<p><strong>查看触发器</strong> show triggersG</p>
<p><strong>通过查看系统表查看触发器信息</strong>use information_schema; select * from triggersG</p>
<p><strong>删除触发器</strong>drop trigger 触发器名字</p>
<p><strong>查看错误信息</strong> show warnings;</p>
<p><strong>查看支持的存储引擎</strong> show engines; 或 show variables like ‘have%’;</p>
<p><strong>查看默认存储引擎</strong> show variables like ‘storage_engine% ‘;</p>
<p><strong>查看MySQL的帮助文档目录列表</strong>help contents;</p>
<p><strong>查看数据类型</strong>help data types;</p>
<p><strong>显示当前年月日</strong>select curdate();</p>
<p><strong>显示当前年月日和时间</strong> select now();</p>
<p><strong>显示当前时间</strong>select time(now());</p>
<p><strong>显示当前年月日</strong> select year (now()) ;</p>
<p><strong>创建存储过程</strong> create procedure 存储过程名字 （存储过程参数：输入/输出类型，参数名，参数类型） 存储过程特性或不写 存储过程的语句；</p>
<p><strong>创建函数过程</strong> create function 函数名字 （函数的参数：参数名，参数类型） 函数特性或不写 函数过程语句；</p>
<p><strong>查看存储过程</strong> show procedure status like ‘存储过程名’ G 或 use information_schema； select * from routines where specific_name=’存储过程名’G</p>
<p><strong>查看函数过程</strong> show function status like ‘函数过程’ G或 use information_schema； select * from routines where specific_name=’函数过程名’G</p>
<p><strong>查看存储过程定义信息</strong> show create procedure 存储过程名G</p>
<p><strong>查看函数过程定义信息</strong> show crate function 函数名G</p>
<p><strong>删除存储过程</strong> drop procedure 存储过程名G</p>
<p><strong>删除函数</strong> drop function 函数名G</p>
<p><strong>创建普通用户账户</strong> create user 用户名 identified by ‘密码’；</p>
<p><strong>创建带权限的普通用户账户</strong> grant 权限参数：select、create、drop等 on 库.表（权限范围） to 用户名 identified by ‘密码’；</p>
<p><strong>更改超级用户root的密码</strong> set password=password（“新密码”）；</p>
<p><strong>利用root用户修改带权限的普通用户密码</strong>grant 权限参数：select、create、drop等 on 库.表（权限范围） to 用户名 identified by ‘新密码’；</p>
<p><strong>利用root用户修改普通用户密码</strong>set password for 用户名=password（“新密码”）；</p>
<p><strong>普通用户更改自身密码</strong>set password=password（“新密码”）；</p>
<p><strong>删除普通用户</strong> drop user 用户名； 或 delete from user where user=“用户名”；</p>
<p><strong>对普通用户进行授权</strong> grant 权限参数：select、create、drop等 on 库.表（权限范围） to 用户名；</p>
<p><strong>收回权限</strong> revoke 权限参数：select、create、drop等 on 库.表（权限范围） from 用户名；</p>
<p><strong>收回所有权限</strong> revoke all privileges,grant option from 用户名;</p>
<p><strong>计算时间差</strong> timestampdiff(interval, time_start, time_end)可计算time_start-time_end的时间差，单位以指定的interval为准，常用可选：second、minute、hour、day、month、year。</p>
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